Abstract: A process for recovering fatty acids and/or rosin acid with a high purity which comprises first introducing a tall oil skimming soap or a tall oil soap into a thin film evaporator equipped with a rake in which the clearance between the blade tips and the surrounding evaporator wall is zero or not more than 1 mm, heating the same at a temperature higher than the melting point of the soap contained therein to evaporate and remove water and unsaponifiables, and then adding an alkali to the thus obtained crude soap to saponify the same, thereby decomposing the esters of rosin acid and fatty acids with sterols and other alcohols; or first saponifying a tall oil skimming soap or a tall oil soap with an alkali to decompose esters of rosin acid and fatty acids with sterols and other alcohols, and then introducing the thus obtained saponification product to the above-said thin film evaporator equipped with a rake, heating the same at a temperature higher than the melting point of the soap contained therein to evaporat